GAITHERSBURG, Md. (WUSA) -- This prom and graduation season, 9 Wants You To Know about yet another way teenagers are sneaking alcohol into their celebrations. They're pooling their money and paying cash to rent local hotel rooms.

"Hi. I want to order a bottle of Red Diamond Merlot."

That was the voice of a teenager, working for Montgomery County Police on a Friday night. She orders alcohol through room service at this Gaithersburg Marriott near the Rio Entertainment Complex and waits behind the door of Room 827 to see if it will come.

Minutes later, it does. And the server asks, "Do you want me to bring it in?"

The girls respond, "Yes, please."

The server brings the bottle of wine right inside the room. No questions asked. That's when police emerge and Officer Bill Morrison says to the server, "Hi. How are ya?"

She responds, "Good. How are you?"

"Come on back inside. County police," says Morrison. "You didn't ask for id, did you?"

"No, I didn't," says the server.

She is asked to call her manager. Police explain that checking for identification is especially important at this time of year-during prom and graduation season.

Says Morrison, "It's not the end of the world for her. I've explained to her everything."

Our next stop: the Hilton Washington North in Gaithersburg. Room 904. The young women who order the wine are 17 and 19 years old, and look their age.

Again, wine is delivered, but this time, the server asks for id. And the 17 year-old hands over her driver's license-with her real birth date: 1994.

"She left with my id, but it's still sitting here," says the 17 year-old, referring to the bottle of wine, sitting on the dresser.

The girls are caught off guard when the server goes to call her manager, but leaves the bottle of wine in the room.

Says Morrison, "I couldn't believe it. She left the wine with kids."

The server returns and asks for another ID. By then, it's too late.

Officer Morrison asks the server, "Where's the wine?"

"It's right there," she says pointing to the dresser.

Morrison asks, "Where did you go?"

She responds, "I went to make sure that the ID was okay."

Morrison inquires, "Where'd you leave the wine?"

She replies, "I left it over there."

Police issue her a citation, and again, call in a manager. Lee Williams of Montgomery County's Department of Liquor Control explains, "Your server did a great job, up until the fact that she took the underage person's id, left the wine in the room for about five minutes."

The manager says, "She checked the ID though."

The manager and his server are defensive.

It's not what we caught on video, but the server says, "Yeah, I told her I couldn't serve her, but I wasn't sure. So I came back."

Officer Morrison tells her, "All you had to do was take the wine. You can't give them the wine and leave it here."

The manager jumps in to say, "She was only gone five minutes."

Again, both the server and the hotel are cited.

The manager throws up his hands in disgust and says, "Okay, fine, write us up."

This is the Hilton's third violation in the last four years-which means a mandatory hearing before the liquor control board, where their license could be suspended.

"These kids rent the rooms, and have all their friends in, and they party," says Sgt. Mark White of the Montgomery County Police Department.

Police say parents seem to have no clue their kids are pooling their cash for a $100 hotel room.

Says Sgt. White, "There can be anywhere from 5 to 10 kids, to 15 to 20 kids. Or larger."

Our final stop of the night: the Holiday Inn Gaithersburg, Room 612.

"Hello. I would like to order a bottle of Copper Ridge Merlot," says the 19 year-old volunteer.

This server asks for id and refuses to deliver the wine when she realizes the girls are underage.

Officer Morrison says, "So that's exactly what we want! So very good job. Thank you very much for carding them and not serving them alcohol."

She earns high praise from police. Afterwards we learn the same server was cited in the past for serving to minors. She clearly learned her lesson.

9 News Now asked the hotels that were not in compliance for interviews and each issued us a statement.

Tom Gilliland with the Gaithersburg Marriott Washingtonian Center writes, "The hotel takes its obligation to comply with liquor laws very seriously and we will be reemphasizing and retraining our associates on the responsible service of alcohol."

And we received this from Chris Daly with the Hilton Washington DC North, "We are aware an alleged violation has occurred and currently are investigating it further. We take all such matters seriously and are reviewing our procedures and policies with all associates."

With three violations now, the Hilton faces a liquor board hearing. That's expected to happen in June.